I agree with this. Ability to resist a push stops making sense at some point.
But Dan also convinced me that you need it to go further. Can one really achieve the bold part without this ability if the opponent does not cooperate?

Sure, if you float someone, they can't push back and they are off balanced, even if they don't quite realize it. You can then make them feel really off balanced by putting them into a hole (a direction in which they are weak). Most of the aikido waza I recall, don't force the person to move in a direction in which they are innately strong.

Even if they person tries pushing harder or leans on you at that point, it just makes it even worse for them.